Windows are responsible for 30% of the heating and cooling loads in buildings. Thin film coatings on glass with color change capabilities could reduce energy consumption by reflecting unwanted radiation and transmitting needed radiation during daylight hours. Dynamic daylight and solar energy control in buildings presently can be achieved using smart windows based on electrochromic, gasochromic, liquid crystal, or electrophoretic devices. However, commercial versions of such technologies have not become popular due to their high costs. Furthermore, electrochromic windows require electrical energy to switch from one state to the other, and liquid crystal windows require continuous energy to remain in the transparent or colored state.
To date, success has been shown only by electrochromic windows in reducing cooling, heating, and lighting energy loads with modulation up to 68% transmission of the total solar spectrum. State of the art electrochromic windows can reduce up to 26% of lighting energy and 20% of peak cooling loads.
In view of the above discussion, it can be appreciated that it would be desirable to have a chromatic devices that can be used with windows that are both effective and inexpensive to produce and operate.